added ISAPLIB sources are a dependent of the Quanto sources.
tweak to allow isaplib to be a symlink
Search local polyml directory before PATH

If there is a local polyml directory, we probably want to use it.
Improve LinratAngleExpr tests

Also, some improvements to the LinratAngleExpr code; mostly formatting,
but also catching parser exceptions properly.
Reduce debug output in normal builds

It's mostly just distracting, and hides warnings.  local_config.ML can
be used to up the levels again for debugging particular problems.
Fix handling of invalid JSON LinratAngleExpr input

We had Null (a variable) instead of Json.Null (a value) as a match
expression, so invalid JSON types would get a zero expression instead of
an error.
Reduce warnings

Mostly just using _ for unused variables, but also making matches
exhaustive.
Only consider dirs for POLY_HOME if they contain a poly executable
Fix "make run"

It now actually loads the heap properly.
fixed unintensional colour change when renaming an angle variable
accidentally left renamers commented out. fixed now
rename avoiding fix
More sensible default left pane size
pushed quick fix for bad rewrite rect
Reorder files in ROOT.ML

I/O code now comes just after the structures it works on, with the
exception of the XML stuff, which is in its own block.  This will
allow us to use I/O code in tests (eg: describing graphs in JSON).
Rename the test graph structures

Put RG into the names, so that we can construct a seperate test graph
type that can test things like edge data.
Rename test-graph-setup.ML to test-rg-graph-setup.ML
Add a new test graph structure

This has a selection of node and edge data types, including "unit"
types, types with strings and types with LinratAngleExprs.

This should hopefully give us better coverage of various bits of code in
the tests.
Rewrite GRAPH tests for new graph type.

This sets up a structure where we essentially test a particular
signature.  There is a functor which tests the functions of the GRAPH
signature on a suitable graph.  We then use this to test the GRAPH
signature function of the Graph, OGraph and BangGraph variants of our
graph type.

Note that this already caught a case where the Graph version of a
function (delete_edge) was correct, but the OGraph version was not (it
threw the wrong exception if there was no such edge).
Use new test graph type for OGraph tests